body {
    margin:0;
    padding:0;
}  
.center{
    text-align:center
}  
  
.btn {
    position:relative;
    z-index: 1000;
    border:none;
    outline:none;
    cursor:pointer;
    overflow:hidden;
    user-select:none;
    background-color: #fff;
    padding: 0;
}  
  
.ripple {
    position:absolute;
    background:rgba(0,0,0,.15);
    border-radius:100%;
    transform:scale(0);
    pointer-events:none;
}  
.ripple.show {
    animation:ripple .75s ease-out;
}  
@keyframes ripple {
    to {
        transform:scale(2);opacity:0;
    }
}  